Sander



M y 1941- c. A. CAMPBELL v 2,243,243 SANDER Filed Jan. 16, 1940 sSheet-Sheet 1 Gttornegs May27, 1941.

c.-A. CAMPBELL v SANDER Filed Jan. 16, 1940 3 Sheets-Sheet- 2 l/y//Wa/.,

Snventor c. A. CAMPBELL 2,243,243

SANDER Filed Jan. 16, 1940 3' sheets-sheets D I IIIII v v 'IIIIIIII May27, 1941.

Patented May 27, 1941 SANDER Charles A. Campbell, .WatertowmaN. Y.,assignor to The New York Air BrakeGompany, a corporation of'New JerseyApplication January 16, 1940,1Se1ial No: 314,173

31 Claims.

This invention relates to sand traps for railway vehicles, andparticularly to such devices for use in high speed trains.

This application is in part a continuation of my application Serial'No.274,295, filed May 17, 1939.

On such trains the required short stopping distance can be attained onlyby very rapid applicationof .the brakes with Very high braking ratios.The approach to wheel sliding even with good rail conditions often is soclose that sanding throughout the train during all'brake applications,or at least during all heavy or emergency applications, is a desirablesafeguard.

In such case, rapid response of the sanders necessary because sandingmust commence at least as soon as the brake application becomesefiective. Sanding must'be certain, so the trap should permit clean-outfunctions which will'unfailing blow ice and mud from the related sandingnozzle. Economy in the use of sand is important because frequentoperation of the sanders must be provided for, and sand storage capacityis limited.

These requirements confiictin a considerable degree and the presentinvention involves the reconciliation of operating factors to ensurerapid, certain and economical functioning under all conditions.-

The sand trap is gravity fed and retains the between the trap and thesand pipe and. is momentarily closed to permit the sand pipe tobesubjected to a clean-out pressure blast preliminarily to actual sanding.

The intercepting valve and its actuating mechanism are novel and haveimproved operating characteristics; a wholly new stirringjet operated byair entering the sand trap at atmospheric pressure is used; andcompensating means are, for the first time, associated with the stirringjet, and serve to equalize the feedingfiow of sand to the ejector andhence to the sand pipe;

The sand trap may be used with any controlling mechanism which willproperly deliver clean-out air and sanding air under pressure, but therelay valve shown has decided advantages and many novel characteristics.

In the drawings:

Figure l is a vertical axial section through-a sand trap embodying theinvention.

Figure 2 is a vertical section on the line-22 ofFigure 1.

Figure'Tisa detail View of a ported nut used in the device.

Refer toFigures '3 to 6. of the wires II and IZ'eXtends throughout thetrain; beingconnected from car to car by the usual jumpers or releasableconnectors. A source" of current conventionally represented as batteryl3is included in the circuit. This is controlled by a normallyopenswitch comprising the contacts M and i5'to which the wires H and 52are connected'and a bridging contactor it which is normally held incircuit-breaking position by the coil compression spring ii, and may beforced to circuit closing'position by the admission of air underpressure through the pipe is to the space below the actuating piston it.

A sanding-valve of any suitable type maybe usedto maintain the pipe i3normally'vented and to admit compressed air through the pipe whensanding is desired. Such a valve may be capable'oi manual operation andmay include'means to operate it asan incident to brake application,particularly emergency brake applications- A sanding-valve suited tothis function forms the subject matter of the patent to Campbell No.2,035,533'issued March 31, 1936.

Mounted on each car, or at any rate, on each vehicle on which sanding isto occur, is a local source of air under pressure diagrammaticallyindicated-by the reservoir 2i, 2. sanding relay valve generallyindicated by the numeral 22 applied to its housing and a magnet orsolenoid winding 23 for controlling the relay valve, the winding 23being connected between the wires II and I2 as, clearly indicated inFigure 3.

The reservoir 2| is charged by any suitable means through a connection 2The charging means is not illustrated but means well-known in r the artare local compressors, reservoir lines extending; throughout the trainfrom the main reservoirat the head of thetrain and restricted Thecircuit made up' charging connections from supply reservoirs formingpart of conventional air brake systems. The reservoir 2| is piped asshown to a port 25 in a so-called pipe bracket 25. This is merely asupporting means for the pneumatic apparatus and is rigidly mounted onthe vehicle. It afiords connections for all pipes in the sander system.Thus, components of the relay valve may be dismounted without breakingpipe connections.

The housing 22 of the relay valve is mounted against one side of thebracket 25 and its outer end is closed by removable cap 21. The housing22 encloses a bushed slide valve chamber 28 and a bushed cylinder 29 inwhich a piston 3| is slidable. The piston 3| is biased to its inward orrunning position (shown in' Figure 3) by a coil compression spring 32.Rigidly attached to the piston is a stem 33 notched to confine agraduating valve 34, which controls ports hereinafter described, in amain slide valve 35 which works on a seat in the valve chamber bushingand controls certain ports formed therein.

The valve 35 has limited lost motion with reference to the piston stem33. The space to the right of the piston 3| and consequently the slidevalve chamber 28, is subject constantly to pressure in the reservoir 2|since a branch of the port 25, clearly shown in the drawings, leads tothis chamber.

To efiect the sanding operation, the piston 3| is caused to movegradually to its left-hand posi-' tion and remain there during thesanding operation. At termination of the sanding operation, the piston3| moves gradually back to the nor-' mal position shown in Figure 3 andcarries out certain valve sequences to be described.

Mounted on the opposite side of the bracket 28 from the housing 22 is avalve housing 35. This housing has a supply chamber 31 fed at a limitedrate by the port 25 through a restricted choke 33. Above the chamber 35and separated therefrom by ported valve seat element 33 is a chamber 4|in free communication by way of port 42 with the space to the left ofthe piston 3!. At the upper end of the chamber 4| is a second valve seatelement 43 which leads toa restricted discharge fitting 45. Coactingwith the valve seat member 35 and the valve seat member 43 isdouble-beat poppet valve 45 which is urged to the exhaust seat by a coilcompression spring 45. Thus, under normal conditions, air under pressurefrom reservoir 2| flows from chamber 3? through supply seat 33 tochamber 4| to port 42 and consequently to the space to the left ofpiston 3|. This equalizes the'pressures on opposite sides of the piston3| so that the spring 32 shifts the relay valve piston tov the normal orrunning position of Figure 3.

The valve 45 is arranged to be operated by the winding 23. There is astem 41 which is connected to the armature (not shown) within thewinding 23, so that when the winding is energized, the valve 45 is movedto close the supply port and open the exhaust port with the result thatthe space to the left of the piston 3| is vented to atmosphere at a ratecontrolled by the restricted exhaust fitting 44. Thus, when winding 23is energized, the piston 3| moves gradually to the left. Ordinarily, thetime required is adjusted to about one-second duration. When thereafterthe winding 23 is de-energized, piston 3| returns to its runningposition (Figure 3) at a rate controlled by the size of the choke 33.This period of return may be slower, in which event a final clean-outblast will have a somewhat longer duration than the initial clean-outblast which precedes sanding.

Connected to the bracket 25 are a sanding pipe 48 and an impulse pipe45. The sanding pipe 48 leads to a single sanding port 5| in the seat ofthe slide valve 35. The impulse pipe 49 leads to two impulse ports 52and 53 also in the seat of the valve 35. The slide valve has threethrough ports, each of which has an extension on the lower face of theslide valve 35 in the direction of travel of that valve. These portsare: a sanding port 54 which coacts with the port 5| and which isconstantly exposed to pressure in the chamber 23; an initial impulseport 55 and a final impulse port 55. The two impulse ports arecontrolled by the graduating valve 34 which either blanks the upper endsof the ports 55,55 or connects the selected one of them with the slidevalve chamber 28 by means 0 of a through port 51.

The location of the ports is shown in the drawings and their functionscan be described by referring to Figures 3 to 6.

Figure 3 shows running position. The

sanding port 54 is to the right of the sanding port 5| so that air isnot supplied to the sanding pipe 48. Initial impulse port 55 registerswith impulse port 53 but is blanked by the graduating valve 34. Port 51in the graduating valve .registers with the final impulse port 55 butthat "'"port is blanked at the seat of the slide-valve so no air issupplied to the impulse pipe 49. Assume now that winding 23 isenergized. Venting of the space to the left of the piston 3| 3;, .causesthe piston to move gradually to the left; slide valve 35 remains atrest, graduating valve 34 reaches the position shown in Figure 4 just asthe stem 33 starts to move the slide valve 35. Port 51 in the graduatingvalve now exposes io initial impulse port 55 so that air under pressureis supplied to the impulse pipe 43. This supply continues until thelarge lower end of port 55 passes beyond port 53. Before this occurs,port 54 will have opened into port 5|, admitting air asunder pressure tosanding pipe 48.

Figure 5 shows the valve in the position when the piston 3| is at .itsouter limit of travel. When the winding 23 is deenergized, piston 3|starts to move to the right. The graduating valve 34 first shifts sothat port 51 registers with final impulse port 55, as shown in Figure 6,while sanding port 54 is still in communication with sanding port 5|.This occurs just as the stem 33 picks up main slide valve 35. The effectis to admit air through ports 51, 55, 52 to the impulse pipe 49 whileair is being supplied to the sanding pipe 48. Continued motion of thepiston 3| to the right shifts main slide valve 35 and the supply of airto both pipes is terminated at or about the same time, the partsresuming the position shown in Figure 3.

Thus, the sequence of flow is as follows: Admit air to the impulse pipe,then admit air to both pipes, then cut off flow of air to the impulsepipewhile continuing to admit air to the sanding pipe. Flow to thesanding pipe then continues as long as sanding is desired. To terminatesanding the piston 3| is caused to move back to running position (Figure3). The

first effect is to admit air under pressure to the impulse pipe whileadmission to the sanding pipe continues, then the flow to both pipes isterminated.

The cycle may be modified somewhat. For

example, it is not necessary to the operation of the sand trap-thatfiowtothe sanding pipe continueaft'er the final impulse-flow is commenced.The. operation. described is typical of one to which the sandftrap. now.about to be described issuited.

ReferringtoEigures. 1; 2 -and 3, the sand trap structurev is supportedas a unit by a bracket member 61 which ismounted either on the car bodyor on the truck by means not illustrated in; thedrawings... The detailsof support have nothing. to. do. withthe present invention and are.subject. to mlodificationaccording to the particular. scheme. adopted,for a particular installation.

Member 615 hasan impulse air passage 52, a

sanding. air passageEZ-land a sand hopper 64- andazlargeatmospheric airpassage 65 which is designedto; furnish .air.-to the stirring jet, aswill beexplai'ned; The passage 6.5 iscored in aside boss 66..whichprojects into the sand hopper a l at one side and which. carries ahubfil with vertical guideway formed. therein. The particularform. of thesand hopper 64 is not important and; is. sufiiciently i lustrated in thedrawings. It is somewhat contracted-at its lowerend; the. dischargepassage at the lower end being; defined; by an. inserted bushing 58-which isthreadedjnthe member 6 and which preferably. is made of;wear-resisting material.

To supply. air to thepassage iii), an atmospheric intake pipe6.9.isthreaded into the upper end ofithe boss 56. It affords alargecapacity flow passage and is open toatmosphere at itsupper end whereitisprotected by. any suitable means such. as. ascreen and waterdeflecting bafiie so that-air may freelyenter the pipe Bil-but will notdraw in any fluidslwhich wouldaffect the operation of thetranparticularly water.

Overlying. the-i boss 6.5. and the hub 61 and encircling the pipe 6.9 isa horizontal screen H which is, supported. at itsseat for gasketl21andwhich is held. down at its center by a machine screw 13threadedinto the upper end of; the hubfil.

The sand box proper is indicated at 14, but only thelower portionthereof is illustrated because it may assume various forms according tothe particular class of service in which the sander is used. A verticalcylindrical sand screen 15 is shown as mounted in the sandbox i4andprojecting upward from the plane of. the gasket F2; The use of suchscreens is. optional.

Theclean-outline 49 is connected with the clean-out airpassage 62 bywayof a reinforced unionfitting 18 of aform standard in the air brake artand a check valve fitting 11. So far as is material to the invention,the fitting 1'! contains aqdisc check valve 78 urged in a closingdirection by a coil compression spring 19, the valve being arranged toopen under flow from the passage 49 to the passage 62. and close againstreverse flow.

The sanding pipe connects with the sanding air passage 63 by way ofanother reinforced union fitting BI and a strainer fitting 82. This isconstructed. of two separable parts threaded together. and confiningbetween them a screen 83; The. purposeof this screen is to protect therather small. sanding air nozzle from scale or rust which might clog it.

It will be observed that the sand box Id can be removed without.dismounting the pipe connections and the same is true of the sand trapbody. 84;.which is: bolted. against the bottom of the; bracket memberand sealed: thereto by periphery on the in Figure 3. They are ofconventional form.

The body 84 includes continuations of the passages 62 and 63 and thesecontinuations are given the same reference numerals because they are ineifect the same passages. There is also inthe body 84 a sand passage 85to which the sand hopper 5 t" delivers. In this passage thereisanupstanding boss 86' upon which rests the lower end of a stem 8 whoseupper endis slidably guided for vertical movement in the hub 61.The-stemfi'l carriesan umbrella member 88 which, when the device isassembled, acts as a sand deflector because it is positioned abovethe-bushing 68. Under these conditions, it controlsthe delivery ofsandthrough the bushing .68, but if the body 84be removed, descent ofthe umbrella 88 causes it to function as a valve, closing the-passagethrough the bushing 68 and preventing the escape of sand in the eventthat the-body 8k is removed for inspection or repair.

An important-reason for using aseparate bushing $8 is to-facilit'ateinsertion'of the stem 87 and umbrella member 88;

Formed in the body 84 below and slightly to one side of the port throughbushing 68 is a sand retaining chamber 89 which is generally cylindricalin form and around which the sand passage 85- curves so as to enter thesand retaming chamber from beneath. While the chamber. 89"- has beendescribed as generally cylindrical, the chamber with-the approachpassage 85 forms asortof snail shell housing.

On the opposite side ofthe chamber 89 from the approach passage 85-is anatmospheric air chamber 91. This is closed by removable cap 92.andcommunicates atits top freely with the atmospheric air chamber 65.and, hence, with theair. inlet pipe 59. An auxiliary atmospheric port 93connects the chamber 91 with t e sand retaining chambertii. This porthas a regulatory. function which determinesits size, and, in certaincases, this port can be omitted; Its function is to by-pass the stirringjet about to be, described, and by. permitting a limited flow ofiairbetweenchambers 89and 9!, it varies the compensating. action of thestirring jet.

Thestirring. jetis in the form of a nozzle tube M-which discharges belowthe normal sand leveljindicated-in Figure 2 by the legend SL. This levelis not very precisely maintained. It representsthe angle of. repose ofthe entering sand afterflowing. downward through the hopper 64-andiapproach passage 35. Sanddoes not flow freelyv upward. In fact, theline SL represents the sand. level commonly attained. This may bedescribed as the lowest surface level encountered. in service,.it beingunderstood that vibration, centrifugal effects rounding curves andbuffing shocks, etc;, would cause some shiftingof the sand. and theoccasional attainment of sand levels higher than the usualzsand level.The variations of sand levels lead to the provision on the upper face ofthe nozzle tube 94 of a so-calledcompensating slot 955. This slot isexposedfor the greater part of its length when the sand: does not riseabove the line SL and is nozzle iSLiIISEItGd through aseat drilled inthe body 84. It is shouldered to limit its insertion and is slotted sothat its alignment is determined by the pin 91. Nozzle tube 94 is heldin place in any convenient way, a machine screw 98 being illustrated asused for that purpose.

It may be helpful to explain at this point that sand is fed to thechamber 89 by gravity flow but is discharged therefrom only by theoperation of an air ejector. When the ejector operates, the pressure inthe chamber 89 is reduced below atmospheric pressure because enteringflow of the air through the approaching sand is practically cut off bythe sand. As a result of this reduced pressure, atmospheric air flows byway of the pipe 69, passage 65 to chamber 9i. From this, a part of itflows freely through the port 93 and the remainder flows through thestirring nozzle 94 which directs it against the approaching sand andperforms two useful functions: it resists the unduly rapid approach ofthe sand and while holding the sand back stirs up a fog of sandparticles which flow upward through the chamber to the ejector. Thisstirring action is modulated by the compensating slot 96. If the sandlevel is high, that is,

above the line SL, more of the slot 96 is blinded and the stirringaction is intensified. Since this stirring action resists the approachof sand, the effect is to equalize the sand flow and to assure thatdesirable operating condition in which a rather meager quantity of sandis entrained in a rapidly flowing current of air leading to the point ofsanding.

The stirring nozzle is operated by air under atmospheric pressure, andthis stirring nozzle, in conjunction with the compensator, hasdemonstrated great effectiveness in stabilizing the rate of sanddelivery despite disturbing conditions such as vibration, shock, flowcharacteristics of the sand, and the like. The by-pass port 93 modifiesthe effective pressure differential which causes air to new through thenozzle 94 and hence is in the nature of a convenient means for adjustingthe action of the stirring nozzle. Once the proper size of port 93 for agiven class of service has been determined, it need not be changed.

The discharge connection from the chamber 89 provides a horizontalpassage concentric with the axis of the chamber 89 and above the levelof sand (SL). The details of construction are best shown in Figure 1,and involve a wear-resisting insert WI and a rubber bushing I02 which,together, produce a Venturi throat or contraction suited to the ejectorfunction which is characteristic of the sand delivery mechanism.

The bolted flange I03 connects a flexible hose I04 which leads to adistensible rubber nozzle I05, not herein broadly claimed because it isthe subject matter of other applications, but nevertheless performing auseful function in conjunction with the particular sand trap which ishere disclosed. The nozzle I05 is directed to the angle between therail, indicated diagrammatically at I06, and the wheel indicateddiagrammatically at I01.

Projecting through chamber 89 and axially aligned with the throatproduced by the members i0! and I02 is a nozzle structure which, duringsanding is retracted so that when the nozzle directs a jet of air intothe throat, air and suspended sand are drawn from the chamber 89 anddischarged through the throat. During the clean-out operation, however,the nozzle moves toward the throat and an elastic member which servesalso as a protecting sleeve seals on the member IOI. Thus, sand is notwithdrawn from the chamber 89 during the clean-out operation. On thecontrary, air under pressure is delivered by the impulse pipe and laterby the sander pipe or by both pipes together to develop pressure in thesanding hose I04. If the hose is clogged at the nozzle I05, dilation ofthe nozzle will clear the obstruction.

Air is delivered through the impulse pipe only for a short interval, atthe commencement and again at the termination of the sanding operation.Hence, if the sand pipe is clear, no substantial pressure will bedeveloped in the hose I04 but if the nozzle is obstructed the pressurewill be very rapidly developed and even though the impulse pipe ceasesto deliver air the sand pipe will operate to maintain the pressuredeveloped until clearing occurs. At such time, the check valve I8performs its intended function of preventing loss of pressure by backflow of air through the impulse pipe.

With this general statement of operation, the purpose of theconstruction now about to be explained can be followed.

Bolted to the body 84 is a cap I08 in which are formed extensions of theports 62 and 63, these extensions bearing the same reference numerals.The cap I08 overlies a chamber I09 formed in the body 84 and clamps atits periphery a flexible diaphragm III. This is of rubberlike materialand has an annular corrugation to assure adequate motion. It is backedup by a suitably formed diaphragm plate H2 which is formed integrallywith a tubular stem H3. The center of the diaphragm is clamped to thehub of the plate H2 by a ring or washer H4 and by a nut H5 threaded onthe stem as shown. This nut is radially slotted on both faces, the slotsleading to an annular groove which surrounds the threaded portion. Theslots and the annular groove afford communication from the space to theleft of the diaphragm I II to drilled ports H6 which lead to theinterior of the hollow stem H3. The ring H4 encircles and hence does notblind these ports. The purpose of slotting both faces of the nut is toassure that it can not be so mounted as to blind the ports H0. Theconstruction of the nut H5 is clearly indicated in Figure '7.

The tubular stem I I3 is guided at its outer or rear end in a bushingH'I pressed into an opening suitably located in the cap I08 and isguided at its inner or forward end in :a sleeve-like bushingHB whichseats in a cavity formed in the inner face of the chamber I08 to receiveit. The bushing H8, where it seats in the cavity just mentioned, ischanneled and functions to confine a bead H9 on a thimble-like memberI2I. Member I2I is formed of rubber-like material and performs the dualfunction of protecting the guideway in bushing H8 from sand and ofaffording a conical valve surface I22 which coacts with the bushing IOIto seal the chamber 89 from the combining throat i02. The end portionwhich carries the valve I22 encircles a flange on a nipple I23 which isscrewed into the inner end of the hollow stem H3. The construction isclearly shown in the drawing and need not be elaborated.

While the sleeve I22 may be vulcanized or cemented to the nipple I23,this is a matter of design.

The diaphragm plate H2 is urged tothe left and the bushing I I8 is heldto its seat by a coilcompression spring I24 which is confined betweenmembers I !3 and H8 under suitablestress and which yields when thediaphragm III is subject to pressure. This pressure arrives by way ofthe port 62 which, as is clearly shown in Figure 1, discharges into thespace to the left of diaphragm III.

Pressed into the bore of the hollow stem H3 and wholly Within the portsH6 (50 that the latter are not obstructed thereby) is the sand-- ingtube. This communicates through a bore I25 with the sanding passage I53already described, the sanding passage leading to the space to the leftof the guide bushing Ill. The tube I25 is further sustained by theradial pins I2'I. The sanding nozzle tip I28 is threaded into the innerend of the tube I25 and is provided with a flaring discharge port I29 asshown. The parts I25 and I28 enclose a valve chamber in which is freelymounted a ball valve ISI. This serves as a check valve to prevent backflow to the tube I25 from the nozzle I28. I

Slots I 32 cut in the inner end of the nozzle I 23 prevent this ballfrom acting as a valve to resist outward flow from the tube I25 to thenozzle I23.

An equalizing port I33 connects the top of the chamber 89 with a chamberI39 to the right of diaphragm III. A felt plug I34 is screwed intothreads formed in one end of the by-pass port I 33 and serves as a sandexcluding filter.

The operation of the trap can be briefly traced. Under runningconditions, the whole system is vented. With a control relay such asshown in Figur 3, the venting is through the sanding hose I5 1, but thesubstitution for control valve 22 (Figure 3) of a valve which would ventthe sanding line 48 or the clean-out line 49, or both, is contemplatedin certain cases and is mentioned here merely to indicate that the trapis not dependent for operation exclusively on venting through thesanding hose.

When the sanding relay valve 22 reaches the position of Figure 4, airunder supply pressure is delivered to the cleanout line '49. Then itpasses check valve it, forces diaphragm III to the right and causes thevalve element I 22 to seal on the bushing IIII. The restriction offeredby the ports I I 5 is sufiicient to insure response of the diaphragm III, but air immediately flows through H6 and through the interval betweenthe parts I 25, I28, and the hollow stem 'I I3, so that supply pressureis quickly built up in the hose we provided the nozzle N95 is at thattime clogged. If it is not clogged, there will be no substantialdevelopment of pressure. The development of pressure dilates the nozzleI95 if it be clogged and assures immediate clearance thereof.

When the relay valve I22 arrives at the position of Figure 5, the supplyair to the clean-out line 49 has been cut ofl'but the check valve I8prevents back flow. In the position of Figure 5, air is supplied to thesanding line 48 under full pressure and since at this time the valve I22is closed against the bushing II, the sanding air will continue tomaintain clearing pressure in the sanding hose and nozzle I05 if thenozzle N55 is still obstructed. If for any reason it should fail toclear, no sand can be delivered from the chamber 89 to the hose lu l.Assuming, however, that the nozzle was clear at the commencement ofsanding Or is cleared immediately thereafter, the dissipation ofpressure through the ports I I6 allows the spring I 24 to restore thenozzle to the position shown in Figure 1 so that air from the sandingport 63 discharging through the nozzle I28, I29, will draw ai'randentrained sand from the chamber 89 and discharge them through the throatI62 to the sanding hose I64 and nozzle I05- At the termination ofsanding, the sanding relay 22 progresses to the position of Figure 6 atwhich time the supply of air to the sanding pipe id is continued and ashort impulse is delivered to the clean-out pipe-d9. The eifect is toforce the diaphragm III and the nozzle structure to the right,cutting'off the flow of sand and causing the last air to, sweep the hoseNM and the nozzle I85 clear of sand. This final clean-out is usefulbecause it reduces the tendency for clogging to occur.

During the sanding operation, the stirring nozzle 94 and itscompensating slot 96 perform the compensating function alreadydescribed.

The invention provides a trap which responds very rapidly to and willinitiate sanding before a brake application becomes effective, eventhough the sanding function be initiated by the brake-applying movementof some part of the braking system, such, for example, as the en gineersbrake valve or an automatic brake controlling valve device at the headof the train. Both of these schemes of operation are known and neitheris illustrated in the present case because it is not a feature of thepresent invention. Sand is used economically and delivered to the railwith sunicient velocity to ensure effective operation at the anglebetween the wheel and rail. Flow irregularities which might be inducedby vibration, centrifugal efiects, and buffing shocks are eliminated,or, at any rate, substantially reduced by the compensating action of thestirring jet.

What is claimed is: V

1. In a-sand trap, the combination of a chamber for retaining sand;means for supplying'sand thereto; a pneumatic ejector serving when inoperation to withdraw sand from said chamber; a sanding nozzle to whichsaid ejector delivers sand entrained in a current of air; and a stirring"nozzle having an air supply connection and arranged to discharge astirring jet beneath the lowest level of sand in said chamber, saidnozzle having a compensating port arranged to be exposed above the sandmore or less accordingly as the level of sand in the chamber is low orhigh, whereby the activity of the stirring jet is modified.

2. In a sand trap, the combination of a cham ber for retaining sand;means for supplying sand thereto; a pneumatic ejector serving when inoperation to withdraw sand from said chamber,

and also to establish sub-atmospheric pressure in the chamber; a sandingpassage to which said ejector delivers sand entrained in a current ofair; a stirring nozzle arranged to receive air from the atmosphere anddirect it in stirring relation to sand in said chamber; and a restrictedsecondary inlet for air at atmospheric pressure leading'tosaid chamberabove the normal level of sand therein and serving to modify theintensity of action of the stirring nozzle. 7 I

3. In a sand trap, the combination of a chamber for retaining sand;means for supplying sand thereto; a pneumatic ejector serving when inoperation to withdraw sand from said chamber; andalso to establishsub-atmospheric pressure in the chamber; a sanding passage to which saidejector delivers sand entrained in a current of air; and a stirringnozzle, arranged to receive air from the atmosphere and discharge itbeneath the top of sand in said chamber, said nozzle hav-' ing acompensating port arranged to be exposed more or less accordingly as thesand level in the chamber is low or high, whereby the stirring action ismodified to stabilize the delivery of sand to the ejector.

4. In a sander, the combination of means forming a generally cylindricalchamber with its axis approximately horizontal; an ejector throatleading approximately axially from one end of the chamber; a sandingnozzle connected with the discharge end of said throat; an air jetnozzle directed across said chamber toward said throat; means forming agravity approach passage for sand which passage curves around saidchamber and enters the same approximately tangentially from beneath; astirring nozzle arranged to direct an air jet against the entering sand;and connections for supplying air under suitable pressures to said jetnozzle and stirring nozzle and for supplying sand to said approachpassage.

5. In a sander, the combination of means forming a generally cylindricalchamber with its axis approximately horizontal; an ejector throatleading approximately axially from one end of the chamber; a sandingnozzle connected with the discharge end of said throat; an air jetnozzle directed across said chamber toward said throat; means forming agravity approach passage for sand which passage curves around saidchamber and enters the same approximately tangentially from beneath; astirring nozzle, having an atmospheric supply connection, and arrangedto discharge into said approach passage beneath its junction with saidchamber; and connections for supplying air ruider pressure'to said jetnozzle and sand to said approach passage.

6. In a sander, the combination of means forming a generally cylindricalchamber with its axis approximately horizontal; an ejector throatleading approximately axially from one end of the chamber; a sandinnozzle connected with the discharge end of said throat; an air jetnozzle directed across said chamber toward said throat; means forming agravity approach passage for sand which passage curves around saidchamber and enters the same approximately tangentially from beneath; astirring nozzle, having an atmospheric supply connection, directedobliquely downward into said approach passage and dis-' charging againstthe entering sand flow, said nozzle having a lateral compensating portarranged to be variably blinded by the approaching sand stream accordingto its depth; and connections for supplying air under pressure to saidjet nozzle and sand to said approach passage.

'7. The combination of means forming a sanding chamber and a connectionfor supplyin sand thereto; an ejector combining throat extending in anapproximately horizontal direction away from one side of said chamberabove the bottom thereof; a jet nozzle in the chamber and directedtoward said throat; an elastic sleeve of rubberlike material encirclingsaid nozzle normally so positioned as to afford an annular passage tosaid throat; fluid pressure operated means for deforming said sleeve insuch a way that a portion of the sleeve forms an annular barrier betweennozzle and throat, and thus isolates said throat from said chamber whilesaid nozzle remains in communication with said throat; and separateconnections, one for supplying fluid under pressure to'said jet nozzle,and the other for supplying fluid under pressure to said fluid pressureoperated deforming means.

8. The combination of means forming a sand ing chamber and a connectionfor supplying sand thereto; an ejector combining throat extending in anapproximately horizontal direction away from one side of said chamberabove the bottom thereof; a jet nozzle in the chamber and directedtoward said throat; an elastic sleeve of rubber-like material encirclingsaid nozzle normally so positioned as to afford an annular passage tosaid throat; fluid pressure operated means for deforming said sleeve insuch a way that a portion of the sleeve forms an annular barrier betweennozzle and throat, and thus isolates said throat from said chamber whilesaid nozzle remains in communication wtih said throat; a sand stirringnozzle having an atmosphere supply connection, said nozzle beingarranged to discharge air into said chamber; a connection for supplyingpressure fluid to said fluid pressure operated deforming means and tosaid throat simultaneously; and an independent connection for supplyingpressure fluid to said jet nozzle.

9. In a sand trap, the combination of means forming a chamber and apassage for delivering sand to said chamber; an ejector throat leadingaway from said chamber above the bottom thereof; a jet nozzle in saidchamber and directed toward said throat; normally open fluid pressureoperated valve means for isolating said throat from said chamber whilemaintaining communication between said jet nozzle and said throat; astirring nozzle having an atmospheric supply connection and arranged todischarge into the lower part of said chamber; and separate fluid supplyconnections, one leading to said jet nozzle and the other connected tosupply pressure fluid to said fluid pressure operated valve means and tosaid throat.

10. In a sander, the combination of means forming a sanding chamber anda sand approach passage leading thereto, said passage entering saidchamber in a generally upward direction; an ejector combining throatleading away from said chamber above said entrance; a sand pipe to whichsaid throat delivers; a nozzle in said chamber and directed toward saidcombining throat and shiftable in the direction of its axis toward andfrom the same; a combined valve and protecting sleeve encircling saidnozzle and connected at its forward end therewith, the valve portionthereof serving to close communication between said throat and saidchamber around said nozzle when the nozzle is moved toward the throat;yielding means urging said nozzle away from said throat; a movableabutment capable when subjected to fluid pressure to overpower saidyielding means and move said nozzle towards said throat; a connectionfor supplying air under pressure to said nozzle; and a separateconnection for delivering air under pressure to said abutment and tosaid sand pipe.

11. The combination defined in claim 10 in which the path of flow fromsaid separate connection to said sand pipe is by way of an auxiliarypassage in the nozzle to and through the throat.

12. In a sander, the combination of means forming a sand retainingchamber and a sand approach passage leading thereto; an ejectorcombining throat leading away from said chamber above the normal levelof sand retained thereby; a sand pipe to which said throat delivers; anozzle in said chamber and directed toward said to said sand retainingchamber throat; fluid pressure Ioperated :motor means :for producingrelative motion between thelnozzleand throat in thedirection of theaxisof :the nozzle; valve means forming at the limit-of their approach aseal between nozzle and throat with-the nozzle in communication with thethroat; yielding means urging said nozzle and throat apart;

a connection for supplying air under pressure to said nozzle; and aseparate'connection for supplying air under pressure to said motor-means and to said sand pipe.

13. In a sander, the combination of means forming a sand retainingchamber and a sand approach passage leading thereto; anejector-combining throat leading away from'said chamber above the normallevel of sand'retained'thereby; a sandpipe to which said throatdelivers; a nozzle in the chamber and directed toward said throat; fluidpressure operated motor means .for .producing relative motion betweenthe nozzle and throat in the direction of the axis o'f'the nozzle; valvemeans forming at the limit of their .approach a seal between nozzle andthroat with the nozzle in cormnunicationuwith the throat; yield- I ingmeans urging said nozzle and throat apart: a separate connectionforsup-plying air under pressure to said motormeans and .to .said sandpipe; and a check valve arranged topreventback flow throughthe'lastenamed connection.

14. In a sand trap,'.the combination of achamher for retainingsand;means for supplying sand thereto; a pneumatic'ejector servingwhenlinroperation to withdraw sand from saidchamber; and

also to establish sub-atmosphericpressurein the 3 V chamber; a sandingpassage to which said ejector delivers sandrentrained in.a current ofair; a stirring nozzle, arrangedtoreceiveair from the atmosphere anddischarge it beneath the'top of sand in said chamber, saidnozzlehaving acompensating port arranged to be exposed moreor less accordingly as thesand level-inthechamber is low or high, whereby the stirring action ismodified to stabilize ethe deliveryof-sandlto the ejector; andmeanscomprising aiport of limited capacity for admitting air from theatmosphere independently: of said stirring nozzle.

15. In a sand trap, the combinationofmeans forming a chamberand apassage for :delivering sand to said chamber; an ejector throat leadingaway from said chamber above the bottom ,thereof; a jet nozzle in saidchamber and directed toward said throat; fluid pressure operated valvemeans for isolating said throat from said chamber without interruptingcommunication between said jet nozzle and said throat; a-stirring:nozzle having an atmospheric supply connectionandiarranged to dischargeinto zthelower part of said chamber; and means comprisingaportxofrlirnited capacity for admitting air from the :atmosphere tosaid chamber independently of said stirring nozzle.

16. In a sander, the combination of i'neans forming a sand chamber and"a-sand approach passage leading thereto, said passage entering saidchamber in a generally upward direction; an ejector combining throatleading away from said chamber above said entrance; a sand pipe to whichsaid throat delivers; 'means forming a pressure motor chamber; atubular'member extending through'the motor chamber 'and'a portion of thesand chamber and 'havin'gdtsend directed toward said throat; amovableabutment -connector-l with saidtubular member and-working "in said motorchamber; a longitudinally elastic isleeve, forming a'sand excluding seal'between'said toward the same; an annular member forming a combinedguide for said tubular member and retainer for said sleeve; a springreaching between saidmovable abutmentand annular member to retain thelatter and urge the abutment in a direction away from said throat; anozzle housed in said tubular member and directed toward said throat; aconnection for supplying air under pressure to said nozzle through saidtubular member; a connection for admitting air under pressure to saidmotor chamber to react against said abutment in a direction to overpowersaid spring; and means comprising a restricted passage within saidtubular member for delivering to "the throat a part of the air suppliedby the lasts-named connection.

17. In a sander, the combination of means forming a sand chamber and asand approach passage leading thereto, said passage entering saidchamber in a generally upward direction; an ejector combining throatleading away from said chamber above said entrance; a sand pipe to whichsaid throat delivers; means forming a pressure motor chamber; a tubularmember extending through the motor chamber and a portion of the sandchamber and having its end directed toward said throat; a movableabutment connected with said tubular member and working in said motorchamber; a longitudinally elastic sleeve, forming a sand excluding sealbetween said chambers around said tubular-member, said shifted towardthe same; an annular member forming a combinedguide for said tubularmember and retainer for said sleeve; a spring reaching between saidmovable abutment and annular member .to retain the latter and'urge theabutment in a direction away from said throat; a nozzle housed in saidtubular member and di- "rected toward said throat; a connection forsupplying air under pressure to said nozzle through saidtubular member;a connection for admitting airunder pressure to said motor chamber tore- *-act against said abutment in a direction to overpower said spring;means comprising a restricted passage within said tubular member fordelivering to the throat a part of the air supplied by the last-namedconnection; and a stirring jet nozzle having an atmospheric supplyconnection and arranged to discharge approximately at the junction ofthe sand approach with the sand chamber. 7

'18. In a sand trap, the combination of means "forming a chamber and apassage for delivering sand to said chamber; an ejector throat leadingaway from said chamber above the bottom thereof; a jet nozzle directedtoward the entrance end of said throat; a fluid pressure motor subjectin one direction to pressure in said chamber and having on opposedworking space; an annular valve connected with said motor to be movedthereby-in a-closing direction when pressure fluid is admitted tothe-working space of the'motor, said valve when closed serving to closethe an nular interval between the jet nozzle and the entrance end of thethroat while maintaining communication between the nozzle and throat;means biasing said valve toward open position; means for admitting airat atmospheric pressure to said chamber; means providing a restrictedcommunication between the working space of said motor and said throat;and separate connections for supplying air under pressure to said nozzleand to said working space.

19. The combination with the structure defined in claim 18 of a one-wayvalve interposed in the path of supply of pressure fluid to said workingspace, said Valve opening to permit flow to the working space andclosing against reflux therefrom. 1

20. The combination defined in claim 18 in which the connection betweensaid working space and said throat comprises a separate and restrictedpassage associated with said nozzle.

21. In a sand trap, the combination of means forming a chamber and apassage for delivering sand to said chamber; an ejector throat leadingaway from said chamber above the bottom thereof; a jet nozzle directedtoward the entrance end of said throat; a fluid pressure motor subjectin one direction to pressure in said chamber and having an opposedworking space; an annular valve connected with said motor to be movedthereby in a closing direction when pressure fluid is admitted to theworking space of the motor, said valve when closed serving to close theannular interval between the jet nozzle and the entrance end of thethroat while maintaining communication between the nozzle and throat;means biasing said valve toward open position; means for admitting airat atmospheric pressure to said chamber, said means comprising astirring nozzle supplied with air at atmospheric pressure and arrangedto discharge at least partially beneath sand in said chamber; meansproviding a restricted communication between the working space of saidmotor and said throat; and separate connections for supplying air underpressure to said nozzle and to said working space.

22. The combination defined in claim 21 in which the connection betweensaid working space and said throat comprises a separate and restrictedpassage associated with said jet nozzle.

23. In a sand trap, the combination of a sand retaining chamber having adischarge passage; means for supplying sand to said chamber; an ejectortype sand discharging means comprising a nozzle and a throat with whichsaid nozzle coacts, said throat being associated with said dischargepassage; a pressure operated intercepting valve for closing saiddischarge passage around said nozzle while permitting flow through saidnozzle to said discharge passage; a sanding connection for supplying airunder pressure to said nozzle; an impulse connection for supplying airto actuate said intercepting valve; means etfective at least when theintercepting valve is operated intercepting valve for preventingdischarge of sand from said chamber; a sanding air connection forsupplying air under pressure to said ejector nozzle; an impulse airconnection for supplying air under pressure to close said interceptingvalve; means effective at least when the intercepting valve is closedfor delivering air from the last-named connection 'to said sanding pipewhile retaining actuating pressure on said intercepting valve, saidmeans comprising a restricted flow connection; and a controlling valveshiftable from an inactive position in which the supply of air is cutoff through a series of three functional positions to said inactiveposition, in the first of which functional positions it serves todeliver air under pressure to the impulse connection and the second todeliver air to the sanding connection alone, and in the third to deliverair at least to said impulse connection.

25. The combination of a sand trap having a chamber in communicationwith atmosphere; means for supplying sand thereto; an ejector nozzle andassociated throat operable by the supply of air under pressure to thenozzle to propel sand from said chamber; a sanding pipe to'which saidthroat delivers; a pressure distensible self-clearing nozzle throughwhich said sanding pipe discharges; a normally open, pressure operatedintercepting valve serving when closed to isolate the sand trap chamberfrom said throat and sanding pipe; at sanding air connection forsupplying air under pressure to said ejector nozzle; an impulse airconnection for supplying air under pressure to close said interceptingvalve; means effective at least when the intercepting valve is closedfor delivering air from the last-named connection to said sanding pipewhile retaining actuating pressure on said intercepting valve, saidmeans comprising a restricted flow connection; and a controlling valveshiftable from an inactive position in which the supply of air is cutoil through a series of three functional positions to said inactiveposition, in the first of which functional positions it serves todeliver air under pressure to the impulse connection and the second todeliver air to the sanding connection alone, and in the third to deliverair at least to said impulse connection.

26. A controlling valve mechanism for sanders of the type having asanding connection to which air must be supplied to cause sanding and animpulse connection to which air must be suppliedfor clean-out purposes,said controlling valve mechanism comprising a slide valve seat having asanding port adapted for connection with said sanding connection, and animpulse port adapted for connection with said impulse connection; aported slide valve on said seat; a graduating valve coacting with saidslide valve to control ports therein; means for shifting said valvesbetween two limiting positions, said valve shifting means affording lostmotion between the graduating valve and the slide valve; and means forsubjecting said valves to pneumatic pressure and thereby supplying airto ports in the slidevalve, the parts being so arranged that in onelimiting position flow to all ports in the seat is interrupted, as thevalve shifting means is moved towards the other limiting position thegraduating valve first moves and opens a communication through the slidevalve to said impulse port and then the slide valve moves and interruptssuch communication and establishes a communication through the slidevalve to the sanding port, upon reverse movement of the valve shiftingmeans toward the normal position the graduating valve first moves andestab lishes a communication through the slide valve with the impulseport, and finally the slide valve moves to normal position andinterrupts communication with both ports.

27. A controlling valve mechanism for sanders of the type having asanding connection to which air must be supplied to cause sanding and animpulse connection to which air must be supplied for clean-out purposes,said controlling valve mechanism comprising a slide valve seat having asanding port adapted for connection with said sanding connection and animpulse port adapted for connection with said impulse connection; aported slide valve on said seat; a graduating valve coacting with saidslide valve to control ports therein; the parts being so arranged thatthe slide and graduating valves control communication to saidconnections; a piston connected to shift said valves and to afford lostmotion as to one thereof; means for su" jecting the backs of said valvesand one side of said piston to air under pressure; yielding means urgingsaid piston in a direction opposed to the reaction of such air thereon;means forming a working space on the opposite side of said piston; acombined admission and exhaust valve means for subjecting said workingspace selectively to atmospheric pressure or to the air un-i derpressure reacting upon the backs of said valves; and electricallycontrolled means for actuating said admission and exhaust valve means.

28. The combination of a source of sand; a sand retaining chamberconnected to be fed continuously by said source and to retain the sandagainst gravity discharge from the chamber; an ejector device includinga jet nozzle and a throat alined with said nozzle, the throat formingthe exit path for sand from said sand retaining chamber and the ejectordevice being operable to feed sand from said chamber when pressure fluidis delivered through said nozzle; a sanding pipe to which said ejectordevice delivers; a pressure operated intercepting valve for interruptingcommunication between said sand retaining chamber and the throat of saidejector device while maintaining communication between the nozzle andthroat; a connection for supplying air under pressure to said nozzle; aconnection for supplying air under pressure to actuate said interceptingvalve; and valve means for controlling the supply of air to each of saidconnections.

29. The combination of a sand retaining chamber open to the atmosphereand adapted to inhibit gravity flow of sand therefrom; means forsupplying sand to said chamber; fluid pressure operated means forentraining sand and discharging it from said chamber; a sanding pipe towhich said discharging means normally delivers; fluid pressure operatedmeans for clearing said sand pipe; and a pressure operated interceptingvalve arranged to be closed by the pressure of fluid which actuates saidclearing means and when closed serving to isolate said sand retainingchamber from said sanding pipe and from said fluid pressure operatedentraining means.

30. The combination of a sand trap having a chamber; means for supplyingsand thereto; an ejector nozzle and associated throat operable by thesupply of air under pressure to the nozzle to propel sand from saidchamber; a sanding pipe to which said throat delivers; a pressureoperated intercepting valve for preventing discharge of sand from saidchamber; a sanding air connection for supplying air under pressure toSaid ejector nozzle; an impulse air connection for supplying air underpressure to close said intercepting valve; means eifective at least whenthe intercepting valve is closed for delivering air from the last-namedconnection to said sanding pipe while retaining actuating pressure onsaid intercepting valve; a controlling valve shiftable from an inactiveposition, in which the supply of air is cut off, through a series ofthree functional positions to said inactive position, in the first ofwhich functional positions it serves to deliver air under pressure tothe impulse connection, in the second to deliver air to the sanding airconnection alone, and in the third to deliver air at least to saidimpulse connection; and electrically controlled means for causing saidcontrolling valve to move through said series of positions.

31. The combination of a sand trap having a chamber; means for supplyingsand thereto; an ejector nozzle and associated throat operable by thesupply of air under pressure to the nozzle to propel sand from saidchamber; a sanding pipe to which said throat delivers; a pressureoperated intercepting valve for preventing discharge of sand from saidchamber; a sanding air connection for supplying air under pressure tosaid ejector nozzle; an impulse air connection for supplying air underpressure to close said intercepting valve; meansefiective at least whenthe intercepting valve is closed for delivering air from the last namedconnection to said sanding pipe while retaining actuating pressure onsaid intercepting valve; a controlling valve shiftable from an inactiveposition, in which the supply of air is cut ofi, through a series ofthree functional positions to saidinactive position, in the first ofwhich functional positions it serves to deliver air under pressure tothe impulse connection, in the second to deliver air to the sanding airconnection alone, and in the third to deliver air at least to saidimpulse connection; and electrically controlled means responsive to adefinite change of energization to cause said valve to move frominactive position through the first to the second functional positionand responsive to a reverse change of energization to return from saidsecond functional position through the third functional position toinactive position.

CHARLES A. CAMPBELL.

